Ruth Bond wrote on Twitter: “Absolutely wiped, poor girl taken far too soon. RIP Megan, hearts go out to her family and friends xxx.”

Callum Talbot said Megan was “such a lovely lass and gone too soon”.

Ellena Davies wrote: “RIP to one of my longest friends Peter MacCallum, so heartbreaking to witness something so horrible.”

Officers have warned people against taking illegal substances.

Chief Superintendent Angela McLaren said: “We are continuing to investigate these deaths and are following lines of inquiry, including the possibility that they may be drug-related. I would remind all persons attending the festival that there is no safe way of taking drugs.

“Anyone who has any concerns for themselves or others at the festival should contact festival staff, police officers or medics for assistance.”

Meanwhile, police have appealed for information after a cash machine was stolen from the festival’s main arena sometime between midnight on Thursday and 7am on Friday.

The ATM contained a “significant” amount of cash, officers said, as they asked any witnesses to come forward.

More than 80,000 revellers are expected over the weekend, with a line-up which includes Calvin Harris and Red Hot Chili Peppers.

T in the Park is being staged at Strathallan for the second time after leaving its previous home at Balado in Kinross-shire.